Parkinson's disease is a degenerative disease of the brain in which dopamine-producing neurons are destroyed. According to "Harrison's Principles of Internal
Medicine," it affects about 1 million people in the United States. The age at onset can be as early as 35, though it is more commonly diagnosed in a person's 60s. Clinical manifestations of Parkinson's disease may be mild initially, worsening as the disorder progresses.
Tremor
Tremor at rest is one of the cardinal features of Parkinson's. It usually starts in one hand, gradually ascends in the same arm and sometimes affects the leg on the same side. After about a year, the tremor will appear in the other hand. It can also affect the lips, tongue and jaw.
These tremors usually have a pill-rolling quality, that is, the movement is similar to that made by the fingers while rolling a pill or coin between them. Severity can vary in the same person over the course of the day, ranging from barely noticeable to disabling.
Slowness of Movement and Rigidity
According to "Harrison's Principles of Internal Medicine," slowness of movement, or bradykinesia, is the most disabling feature of Parkinson's. Patients may have difficulty performing all the ordinary small tasks required during the day. They could have difficulty standing up, walking, turning in bed, dressing and speaking. Patients may walk with a shuffling gait called festination.
Rigidity reduces the range of motion and can lead to pain and cramping in the tight muscles. Rigidity and bradykinesia combine to produce the mask-like face of the patient with Parkinson's and the inability to swing the arms while walking.
Loss of Postural Reflexes
Patients with Parkinson's lose their sense of balance and ability to correct posture. Normally, minute postural correction are automatically and constantly performed throughout the day. When these reflexes are lost, patients walk as though they're about to fall, with the head stooped and the arms flexed. Motion fluctuates between freezing and abrupt starts.
As the disease progresses, the loss of balance is one of the most disabling features. It increases the risks for falls and subsequently for hip fractures, which are a major source of disability in elderly patients.
Psychiatric Symptoms
According to "Harrison's Principles of Internal Medicine," about 50 percent of Parkinson's patients suffer from depression. Depression is considered an intrinsic part of the degenerative illness rather than a psychological reaction to being ill. Cognitive difficulties are common, affecting abilities such as long-term planning and memory. Dementia can eventually affect as many as two-thirds of patients, as stated in "Harrison's Principles of Internal Medicine." Sleep is often disturbed. Psychotic symptoms such as hallucinations and delusions appear. Some patients act impulsively, engaging in compulsive behaviors such as pathological gambling and compulsive shopping. These behaviors are thought to be secondary to treatment with medications that increase dopamine.
References
- "Harrison's Principles of Internal Medicine, 17th edition"; Anthony Fauci et al.; 2008
- Parkinson's Disease Foundation:Symptoms
- "Adams and Victor's Principles of Neurology"; Maurice Victor and Allan Ropper; 2001
